A class of four-coordinate boron complexes is reported that contain both electron-rich and electron-poor functional groups. Judicious selection of donor and acceptor moieties with the use of a boron atom as a separating node yields charge transfer complexes capable of thermally activated delayed fluorescence (TADF). Complexes were prepared by a modular method providing access to a wide range of emission colors. The singlet (S1) and triplet (T1) energies are independently tuned to achieve a small S₁-T₁ gap. Raising and lowering of S₁ and T₁ states can be predicted using cyclic voltammetry, NTO analysis, and spin density distribution as determined using Density Functional Theory; separation of the hole and electron wavefunction for S₁ excitation and delocalization of spin density distribution in the T₁ state can help in achieving negligible S₁-T₁ gap. Although photoluminescent quantum yields of the boron complexes in a host matrix are less than 65%, OLED device external quantum efficiencies of up to 8.1% have been achieved at a luminance of 1000 cd/m². Selection of a boron emitter with a gap of less than 0.01 eV between the singlet and triplet excited state enables the fabrication of a device with low efficiency roll-off and long lifetime.

中文翻译：

---

基于硼的TADF发射器具有改进的OLED器件滚降效率和长寿命

据报道，一类四配位的硼配合物既含有富电子官能团，又含有贫电子官能团。通过使用硼原子作为分离节点来明智地选择供体和受体部分，会产生能够热激活延迟荧光（TADF）的电荷转移络合物。复合物是通过模块化方法制备的，可提供多种发光颜色。单重态（S1）和三重态（T1）的能量可独立调节，以实现较小的S ₁ -T ₁间隙。可以使用循环伏安法，NTO分析和使用密度泛函理论确定的自旋密度分布来预测S ₁和T ₁状态的升高和降低。S的空穴和电子波函数的分离在T ₁状态下的自旋密度分布的₁激发和离域可以帮助实现可忽略的S ₁ -T ₁间隙。尽管主体基质中硼配合物的光致发光量子产率低于65％，但在1000 cd / m ²的亮度下，OLED器件的外部量子效率已达到8.1％。选择单线态和三线态激发态之间的间隙小于0.01 eV的硼发射极，可以制造出具有低效率滚降和长寿命的器件。